Timer for sand mixers



2 Sheets-Shet l W? E Em $1M.

$5.13 evil h F m n E V. n

v. 25, 1.941. A. c. CHRISTENSEN TIMER FOR SAND MIXERS Filed July 10,1940 H e 5 n 6 1L r h PL a a e r U A Nov. 25, 1941. A. c. CHRISTENSENTIMER FOR SAND MIXERS Filed July 10, 1940 ,2 Sheets-Sheet 2 M 9 .3 c ,1L K v m. a y fw rm 0 mm m G 2 mm 7N0 6 TOW Q at; 3.5 uwhu una myIIII'IIIII I nz Eri If JUffea C C/HJ'SZLGTISGH Patented Nov. 25, 1941TIMER FOR SAND MIXERS' Alfred C. Christensen, Chicago, 111., assignor toHerbert S. Simpson, Ch.icago, 111.

Application July 10, 1940, semi not 344,756

4v Claims.

It has been the practice infoundries to-recondition and reuse the sandfrom foundry molds after the removal of castings. The process usuallyconsists in breakingup the previously used sand molds andremoving metalparticles and the liketherefrom before the used sand is deposited in amulling and mixing machine. The used sand is usually first broken up andthen mulled and mixed, after which selected dry ingredients aredelivered into the mixing-crib, to which mixture water in properquantity is added and mixed before the reconditioned sand is dischargedfrom the-mixer for reuse.

The various steps in the treatment of foundry sands have heretoforeusually been manually controlled and it has been necessary to=rely uponan operators ability and discretion as to the duration of the mixingperiods, the percentage of moisture content of the sand to be treated,and the quantity of water to be added for different batches and. kindsof sand.

The present invention relates to an improved type of an automatic timeror control for definitely timing, by electrical control, the duration ofthe various opera tions in a foundry sand mulling cycle, the recordingof the moisture content of the sand, the quantity of-wat'er required tobe added to the dry mixture, and the timing of the discharge of theconditioned product.

It is an object of this invention to provide an automatic time controlfor governing the steps in the reconditioningro'f used mold sand incontinuous types of foundry sand conditioning systerms.

It is also an object oi. this invention to provide a foundry sandreconditioning installation having an autom-atictiming unit connected inthe system and adapted to: be setfor definitely determining the timingof the. various steps in the cycle.- of operations of the reconditioningof foundry sand.

Another object of the invention is the provision of a time, master for;a foundry sand reconditioning installation, with said time masterincluding, a plurality or controls connected with different parts of theinstallation for governing the timing" of the mixing period, as well asthe timing of the introduction of" the various materials andthefinalidischarge of the reconditioned product from theinstallation.

A further object of the invention is the provision of a time master" foruse; in connection with a foundry and reconditioning installation, saidtime master" including a series of automatic timers for governing thevarious steps in the cycle of operations and also including a moisturetester for the: used" sand to definitely determine the quantityof waterto be added to thesand for proper reconditioning of the same.

It isa further object of this invention to provide a foundry sandmixing-machine with a time control unit including amaster automatic timeswitch and av plurality of auxiliary time switches for governing theoperation of the batch delivery door, the timing of the'dry mixing, thedetermining ofthe quantity or water to be added to the mixture,thetimlng of the discharge of the reconditioned sand, and'finally; theresetting of the: timers for repeating the cycle of operations.

It is furthermore an object of this invention to provide av time masterunit for a foundry sand reconditioning machine, said unit= beingconstructed to permit ofeither' automatic control of the diflferentsteps in the cycle of operati'ons of reconditioning sand or manualcontrol of the various stepsv of the cyclefrom thetime master unit.

It is furthermore anajobiect of this invention to provide a sandreconditioning machine with an electrically controlled instrument unitineluding a series of connected timers for governing the operation ofthe complete cycle of operations of the machine, the operation of thecharge admitting doors, the sampling and testing of the water content orthe charge, thetiming of the dry mix period, the timing of the entranceof apredetermined' quantity of liquid to the charge, and eventually; thetimlng of the operation of the discharge doors for releasing thereconditioned product from the machine.

It is an important object of this invention to provide a foundry sandmixing machine with a timing unit for the cycle of operation of themachine, said timing unit being arranged for convenient conversion froman automatic type to a. manually controlled type; and furthermoreincluding'a sand sampler connectedwith a moisture: tester to determinethe quantity of water to bev added to the mixture and the timing of thedelivery of the required. amount of water into the machine.

Still another important object of this inventiorr is the provision ofatiming instrument including a series of connected electrical timersadapted to be conveniently set or adjusted for automatically determiningthe timing of the difierent steps in the cycle of operations forconditioningroundry sands and thelike.

Other and further importantobjects or this Figure 3 is a wiring diagramfor the electrical v control of the cycle of operations ofthe machineand including a circuit diagram for the manual control of the cycle ofoperations.

- As shown on the drawingst, v

- The improved-foundry sand conditioning systern vis illustratedschematically in Figure 1 of .the drawings, with Figure 2 illustratingthe steps in the cycle of operations of the sand conditioning system.The reference numeral I indicates a chargev or batch delivering hopperwhich receives previouslyused foundry mold sand which ist0;berec0ndition ed for reuse. The hopper I,

"at its lower end, is provided with a batch release door 2 whichnormally closes the discharge opening of the-hopper. Pivotally connectedto the .door 2 is the :lower end of a. piston rod or stem 3 which formsa part of an air control mechanism including an air cylinder 4 in whichthe piston is *slid'ably operated. Air pressure is adapted to beadmittedinto the cylinder 4 alternately above and below the head of the pistonby means of the pipes or'air tubes 5 and 8 which connect upwithasuitable supply of air pressure-controlled" by means of a timeswitch unit I, of a selected standard type, the internal wiringconnections of which are illustrated in the wiring diagram of Figure 3.I 'The time switch unit I is mounted in a control board or-casing 8positionedon a suitable support at a selected distance from the sandconditioning machine. This time switch control unit I is provided withan outer minute time set .dial 9 operable by a knob II] and an auxiliaryor inner second time set dial I I. Both of the time dials 9 and I areadapted to be set. with respect to an index mark |2 positioned on thefront face of the casing of the time switch I.

Positioned beneath the sand supply or batch hopper I is a sand mullingand mixing machine consistingof a sand receiving bin or crib I3supported on a pedestal or) base I4. Mulling and mixing mechanisms,designated, as a whole by the reference-numeral I5, are mounted withinthe sand crib I3 and are operable by means .of gear sets disposed withingear housings I6 .and IT. The gear mechanisms or sets within thehousings I6 and I1 are driven by a driving motor-I8. 'Mounted in thebottom of the crib I 3 are two diametrically opposite'discharge doorsadapted to be operated by means of crank arms .I9. Connectedto, thecrank arms I9 are the .lower endsjof piston rods 20 which operate in airpressure cylinders 2| mounted on the side of crib' I3. The lower andupper ends of the air -pressure cylinders 2| are respectively connectedv.with air pressure supply tubes or pipes 23 and 24. The air tubes, 23,and 24' are connected with ,the source of 1 air pressure through,adischarge -presser head .93.

door control time switch unit 25 which is mounted in the control boardor casing 8 and is provided with minute and second time set dials 9 andI I, adapted to be set for controlling the timing of the operation ofthe discharge doors of the machine.

Also mounted within th sand crib I3 is a water funnel 26 into which thesupply end of a water supply pipe 2'! projects. Connected in the watersupply pipe 21 is a control valve 28, on which a water meter 29 issupported. The timing of the delivery of a charge of water into the sandcrib is controlled by means of a water control form of time switch unit33 mounted in the control casing B and being provided with externallyadjustable time set minute and second dials 9 and II.

The quantity of water which is to be admitted into the .sand crib I3 fora given batch of sand, is adapted to be accurately determined by means.of an improved sand samplerand moisture content tester, briefiycomprising a channel-shaped sand sampler pocket or cell 3| positionedbetween the sand crib I3 and the hopper I directly in the path ofmovement of a charge of sand from the hopper into the crib. Mountedadjacent one end of the sampler cell 3| is an air pressure cylinder 32provided with a piston mechanism on one end of which an angle-shapedcut-off cover or snubbing head 33 is mounted for coaction with thechannel-shaped cell 3| to close the top and one end thereof after asample of the entering sand has been deposited in said cell. Compressedair is adapted to be admitted into .the cylinder 32 on opposite sides ofthe piston .nected to a suitable source of air pressure con- .nectedwith the control casing 8.

Mounted in the control casing 8, and controlling the passage ofcompressed air through the tubes 34 and 35, is a control valvemechanism. operable by means of a handle or hand grip lever 35.

Mounted adjacent the opposite end of the sand sampler cell 3|, isanother air pressure cylinder 31 including a piston mechanism on theouter end of which a sand pressing and discharg head 38 is mounted forcooperation with the sand sampler cell 3| to, first slide into one endof the sand sampler cell 3| to compress the trapped sand therein againstthe end closing flange of the head 33. Connected with the ends of theair compressor cylinder 3! are the ends of two air pressure supply tubes22 and 39 adapted to alternately permit air to be admitted alternatelyagainst opposite sides of the piston head within the cylinder 31 tocause operation of the The air supply tubes 22 and 39 are connected witha suitable source of air pressure supply by means of an air pressurecontrol valve mounted within the control casing 8 and operable by meansof a lever or handle 40.

For the purpose oftesting the moisture content of the sand caught in thecell 3|, moisture testing electrode units 4| are mounted in oppo- Themoisture testing units 4| are connected by means of wires or lines :42and 43 to a standard moisture meter 44 which is providedwith a. suitabledial and an indicating hand to register the moisture content of thetrapped sand so that an operator of the machine can determine the amountof additional liquid which is required to be added to the sand in thecrib I3. The control dials 9 and II, of the water CQIL JIQI time switch39, are then set,.so that at a desired time in the cycle of operation'ofthe machine a predetermined quantity of water or other liquid which isto. be added to the sand batch in the crib I3 may be emitted by theliquid supply pipe 2! into the funnel 26 for delivery into th crib.

In reconditioning a batch of sand delivered from thehopper l' into thecrib I3 it often: is desirable to add a quantity of dry substances oringredients into the batch of sand before liquid isadmitted tothemixture. For the purpose of controlling the timing of the admittance ofthe dry materials into the sand a standard drymix time switch unit 45'is mountedin the control casing 8 and is provided with time-set dials 9and H which are adapted to be set so that the batch of sand and the drymaterials addedthereto may be dry-mixed for a predetermined length oftime before the admittance of liquid into the mixing crib l3.

Also mounted in the control box or casing 8 is a total cycle controltime switch unit 46, which is also provided with a set of minute andsecond control time-set dials 9 and II adapted to be set to determinethe length of the entire cycle of operations of the various stepsincluded in the mulling and mixing of a batch of sand to recondition thesame with a proper moisture content.

For the purpose of resetting the various time switches at the end of acycle of operations the control board or casing 8 is provided with areset control time switch unit 41 which is connected up with the variousother time switches in the control casing 8 for the purposeof resettingthe same at a predetermined time in the cycle of operations, to start anew cycle of operations as soon as a previous cycle is completed.

For the purpose of starting and stopping the machine and the variouscontrol units connected therewith the control board or casing 8 hasmounted therein a main three-way control switch 48 which may be thrownfrom an open position into a closed position for the automatic operationof the cycle, or into a second closed position to permit manualoperation of the cycle.

Figure 2 illustrates diagrammatically the cycle of operations of themachine. The entire cycle of operations is represented by the period of360 degrees. When it is desired to start the machine the main controlswitch 48 is closed to cause automatic operation of the machine,starting at the radial line A. The time switch 25, is set to causeoperation of the air pressure cylinder devices 2| to start the cycle atthe radial line A, to, cause the discharge doors of the bin l3 to opento allow discharge. of the contents of the bin. This operation takesplace depending upon the setting of the time dials on the discharge doortime switch and the discharge continues until the radial line B isreached, at which time the time switch causes closing of the dischargedoors of the bin l'3;

At the same time that the discharge doors close the batch release door2, controlled by the time switch 1, is opened to permit a predeterminedquantity of sand which is to be reconditioned to be discharged into thebin I3. The batch gate 2 will remain open until the desired quantity ofsand has been delivered, and, will, then 7 automatically be closed. Thisoperation is indicated by the are C.

During the time that a charge of sand is being delivered from the hopperI into the bin I 3 a sample of the sand is trapped in the moisturetester cell 3| by operating the control levers nected with the watercontrol valve 5|.

3&- andv 40 so that. the moisture meter 4!? will indicate the moisturecontent. of the sand tobe treated. and will permit the attendant todetermine upon the amount of: water or other liquid to; be added to themoisture. This is. done'by the attendant, who sets the water controltime switch 30;

The testing of the sand for its moisture content is. doneqduring aperiodbetween the radial line. B and the radial line D (Figure 2), which isknown as the dry-mixing period and v is: controlled by. the time switchDuring the interval between the. radial lines B and. D the attendantdelivers into the bin l3 any additional dry materials which. are. neededfor the reconditioning of the particular batch of sand. During thedry-mix period the added materials are thoroughly dry-mixed with thesand.

When the dry mixing period is over the water control time switch 30'acts to cause opening of thewater control valve 28 and operation of thewater' meter 29, and keeps the water valve 28 open, depending upon thesetting of the. time switch, until the required quantity of water orother liquid is delivered into the funnel 2G for discharge-L into thedry mixture contained within the crib l3. As soon as the requiredquantity of liquid has been: added the time switch shuts oif. the watervalve 28, and this phase of the operation is indicated by the radialline E in Figure 2.

From this point in the cycle of operations the mulling and mixingmachine continues to operate from the radial line E for the balance ofthe cycle. Just prior to the end of the cycle of operations, at theradial line F, the reset time switch 41 is brought into action toautomatically reset all. of the time control switches.

The total. cycle time switch 46 has the dials thereof set to determinethe length of the total cycle ofoperations. When, the radial line A, inthe cycle diagram, is reached after a complete cycle of operations thebin discharge doors are again opened to permit discharge of thereconditioned sand to begin. the next cycle of operations of themachine.

When it is desired to convert the machine from. automatic operation to amanual or handcontrolled machine it is, only necessary to throw the mainswitch 48 into engagement with the hand control contact of the switch,thereby'cutting off all of the time switches and operating, instead,through manually controlled push button switches such as a doordischarge control switch 49, a batch gate control switch 50, and a watersupply control switch 5|.

Connected with the discharge door control switch 49 is a solenoid valve52.. A solenoid valve. 53' is connected with the batch gate controlswitch 50 and a: solenoid valve 54 is con- The solenoidv control valveunits 52-, 5.3 and 54 are also connected with the. respective timeswitches in the automatic system, as clearly illustrated in the circuitdiagram of Figure 3.

Referring now to Figure 3 of the drawings, the control circuit forgoverning the cycle of operations of the machine comprises power lines55 and 56 for the supply of an alternating current. The power line55 isconnected to an auto matic control contact 51 of the main switch 68; Thesecond or manual control contact 58, of the main switch 48, hasconnected thereto a circuit line 59 which is respectively connected tothe contacts 60-, El and 6 2 of the manually and r are normally open.

operabledischarge control switch 49, 'the batch control switch 50 andthe water control switch 5|. The opposite terminal 63 of the dischargecontrol. switch 49 is connected by means of a line 64 to one terminal ofthe solenoid valve 52. The second terminal 65 of the switch 50 isconnected by means of a line 66 to one terminal of the solenoid valve53, and the second terminal 61 of the switch 5| is' connected by meansof a line 68.to one terminal of the solenoid valve 54. The secondterminals of the respective solenoid' valves 52, 53 .and 54 areconnected by means of a line 69 to the circuit supply line 56.

Included in the circuit are six standard time switches namely, the totalcycle time switch 46, thedry' mixing time switch 45, the water additiontime switch 30, the discharge door time switch 25, the batch g'ate timeswitch 1, and the reset time switch. 41. Each of the foregoing standardtime switches is provided with eight terminal posts, designated by theletters a, b, c, d, e, f, g, and h. In each of the six time switches theterminal posts 9 and h are connected by a connecting bar jand theterminal posts b and f are connected by a connecting bar 74:. In thetime switches 45, 30, 25 and 1, the terminal posts b and c are connectedby a connecting bar I. In the reset time switch 41 the connecting bar isomitted between the terminal posts b and c and instead a connecting bar111. connects the terminal posts and g. In the total cycle time switch46 the connecting bar between the terminal posts I) and c is omitted, aswell as the connecting bar between the terminal posts 1 andg.

Each of the time switches includes a clutch coil 11, a Telechron motor 0and three switch contacts 11, q and r. In the time switches 45, 46, 30,25an'd 1, the three switch contacts p, q In thereset time switchv 41 thecontacts p and 1 are normally open, while the switch contact q isnormally closed.

Connected to the terminal post a of each of the six time switches is aline 10 which is also connected to the power supply line 56. Connectedwith the terminal post I) of the time switch 46 is one end of a line 1|,the other end of which is connected to the terminal post d of the timeswitch 41. The terminal post c of 'the time switch 46 is connected bymeans of a line 12 to the third terminal of the main switch 48. Theterminal post cl of the time switch 46 is connected by means of a line13 to the terminal post 1) of the reset time switch 41. The terminalpost e of the total cycle time switch 46 is connected by means of aline'14 to the terminal post 11 of the discharge door time switch 25.

Referring now to the dry mixing time switch 45, the terminal post 0 isconnected by means of a line 15 to the terminal post 0 of the batch gatetime switch 1. A line 16 also connects the terminal post 0 of the timeswitch 45 with the terminal postc of the discharge door time switch 25.The terminal post d of the time switch 45 is connectedby means of a line11 to the terminal post 0 of the water time switch 33.

Referring to the water time switch 36, the terminal post e is connectedto a line 18, which also connects up with the solenoid valve 54.Referring to the discharge door time switch 25, the terminal post e isconnected by means of a line 19 to the solenoid valve 52. The solenoidvalve 53 is connected by means of a line 80 to the terminal post e ofthe batch gate time switch 1.

Connected to the terminal post 0 of the time switch 41 is a line 8|, theother end of which is connected to the third terminal of the main switch48.

By means of the improved control casing or board 8 connected with thevarious mechanisms forming part of the sand reconditioning system, aselective master timing arrangement is provided whereby the machine maybe operated automatically for production control or said machine may beconverted into a hand-controlled system by selected operation of themain switch 48.

The improved automatic control for the mulling and mixing cycle,together with the means for determining the amount of water to be addedto a sand batch in order to obtain the required moisture content in thesand being mixed, assures uniform and properly conditioned sand to bedischarged from the mixing crib I3 for delivery to a foundry moldforming zone.

Before the operation of the machine is started, a required quantity ofsand which is to be reconditioned is measured off in the supply hopperI, which holds the batch or charge of sand in check by means of theclosed batch gate 2. The threeway main control switch 48 is normallyopen. When an operator desires to start the automatic cycle ofoperations, the switch 48 is thrown into contact with the switchterminal 51. This throwing of the switch to the automatic switch contact51, starts the cycle of operations at the line A shown in the cyclediagram of Figure 2, with the total cycle time switch 46 having the timedials thereof first set to determine the length of the entire cycle ofoperations. At the start of the cycle the discharge doors of the crib I3are closed so that the first stepin the cycle is the operation of thedischarge door time switch 25 to cause the discharge doors of the cribI3 to open, as indicated by the radial line A of the cycle diagram ofFigure 2, allowing the discharge of a fully reconditioned batch of sandto take place from the mixing and mulling machine crib. The dischargedoor time switch 25 has the compound dial thereof set allowing adefinite period of time for the discharge doors to remain open to permita complete emptying of the crib. When the radial line B in the cyclediagram is reached, the discharge doors are automatically closed by thefluid pressure cylinder units 2|, and at the same time the batch gatecontrol time switch 1 causes the fluid pressure cylinder unit 4, tooperate, to open the batch gate 2 of the hopper I, permitting apredetermined charge contained within the hopper to be delivered intothe crib I3. With the delivery of a batch of sand into the crib I3, thedry-mixing period commences and continues for a predetermined period upto the radial line D.

As soon as a batch of sand is delivered into the crib I3, an attendantof the machine delivers the required dry ingredients into the crib, sothat the added ingredients may be thoroughly mixed and mulled with thebatch of sand.

During the time that the batch of sand, which is to be reconditioned,flows from the supply hopper I into the crib I3, the attendant mustdetermine the percentage of moisture content of the sand so that therequired amount of water may be added to the mixture at a proper time,in the cycle of operations. The attendant therefore brings the moisturetester unit into play by manually swinging the air pressure controlhandle 36 to cause the air pressure cylinder mechanism 32 to actuate theangle-shaped sand trapping or snubbing head. 33 'to cause the sametoslide'over the testing pocket or cellp3| to trap a sample of the sand inthe cell 3 1. Followingthe swinging of the handle 36 the control handle40 is oper ated to cause the air cylinder 31 to move the compression orramming head 38. into the closed cell 3| to compress or ram the trappedsample of "sand, thereby permitting the brass electrodes 4| to measurethe pmoisturepontent Qof .the trapped sample of sand, by-the impedanceprinciple by means ;of thegmoisture meter 44, which is connected withthe electrodes 41- by means of the wires 42 and 4.3 and is:set torecordeither in terms of percentage of moisture in the sameor gallons ofliquid to be added "tothe batch. The attendant of the machine is thusableto determine the quantity of Water. which is required to be added tothe dry mixture within the crib l3.

The water control time switch 38 is. accordinglyset by the attendant sothat at a predeter mined time in the cycle ofoperations namely, at theradial line D, in the diagram of FigureZ, the water valve 28 is opened,allowing a predetermined quantity of wateror other liquid to bedelivered by the pipe 21 into the funnel 2 6 for mainder of the cyclefrom the radial line Econtinuously around to the radial line A, when thereconditioned batch thusprepared is discharged from the machine- Justprior to the opening of l the discharge doors of the crib I3 the radialline F indicates the time at which the reset time switch 41 is broughtinto operation to automatically cause resetting of the various timeswitches so that the next cycle of operations of the machine may takeplace.

In operating the moisture tester by means of the hand levers 36 and 40,the hand lever is operated to cause the snubbing head 33 to first moveinto position with respect to the cell 3| and to remain there while thehandle 40 is operated to actuate the ramming head 38 to compress thetrapped sand. As soon as the reading on the moisture meter 44 isobtained the handle 36 is released or reversed to retract the head 33.The pressure in the cylinder 31 accordingly acts to permit thecontinuation of the movement of the snubbing head 38 through the cell 3|so that the trapped sample of sand is discharged from the cell with theretreat of the member 33.

Attention is also called to the fact that when the dry ingredients areadmitted into the crib 13 after a batch of sand has been delivered fromthe hopper I, such dry ingredients may either be manually dumped intothe crib or the same switches. and in turn control the opening andclosing of the crib doors, the" batch gate "and the addition of water,by means of the push button switches 49, 50 and f5l, which are readilyaccessible fromthe controlboard '8. i

In the manual. control of the machine the moisture tester may beoperated by means of the control levers 36 and .40 to determine the moisture content of the sand and the amount of water to be added, may bedone bymanually operating the water valve 28 1 and the meter connectedtherewith... 1 l H In both the "automatic and the manual opera-. tionsof the sand reconditioning system it is not necessary to operate themoisture testing control mechanism and the moisture meter "connectedtherewith, with the reconditioning of each batch of sand. The moisturetesting is-only necessary at selected intervals and shouldzbezdeterminedby the attendant operating or working the machine. It is up to theattendant-todetermine when the moisture tests should bemade and how manybatches can be run on the same moisture setting.

The equipping of said 'mixing :and mulling machines with a time masterunit permitting either automatic control of the various mechanisms ofthe machine, or manual control when desired, provides a continuous sandreconditioning system 'which is idependable vforrcontrolling theproduction and uniformity of foundry system sands; 1

In addition to providingrthe sand reconditiom ing machine with a timemaster for either automatic or hand control, a moisture content testertreatment of is also included for determining the amount of positionfrom the sand reconditioning machine to permit remote control of theoperation of the various parts of the machine, either automatically ormanually, depending upon the operation of the main control switch 48.

It will of course be understood that various details of construction maybe varied widely without departing from the principles of thisinvention, and it is, therefore, not the purpose to limit the patentgranted herein otherwise than necessitated by the scope of the appendedclaims.

I claim as my invention:

1. Means for reconditioning foundry sand comprising in combination acasing containing power-operated mixing and mulling means, a source offoundry sand, a first valve means interposed between said source andsaid casing to control flow of sand from said source to said casing,water supply means including a second valve means to supply water tosaid casing, timed means arranged operable to automatically operate saidfirst valve means, said power-operated means and said second valve meansin timed relation to each other and for predetermined periods of time,means interposed between said first valve means and said casing toindicate the moisture content of the sand flowing from said source, andmanual means operable at will and cooperable with said timing means tocondition the supply of water to said casing in accordance with theinformation on moisture content conveyed to the operator by saidmoisture-indicating means.

2. Means for reconditioning foundry sand comprising in combination acasing containing power-operated mixing and mulling means, a source offoundry sand, a first valve means interposed between said source andsaid casing to control flow of sand from said source to said casing,water supply means including a second valve means to supply water tosaid casing, timed means arranged operable to automatically operate saidfirst valve means, said power-operated means and said second valve meansin timed relation toeach other and for predetermined periods, meansinterposed between said first valve means and said casing to trap asample of the sand, means to indicate the moisture content of thetrapped sample, and manual means operable at will and cooperable withsaid timed means to condition the supply of water to said casing inaccordance with the information on moisture content of the sampleconveyed to the operator by said moisture-indicating means.

3. Means operable in repetitive cycles for reconditioningfoundry sand,said means comprising in combination a source'of foundry sand,power-operated mixing and mulling means, a first valve means interposedbetween said source and said mixing and mulling means to control flow ofsand from the source to said mixing and mulling means, water supplymeans including a second valve means to supply water to the sand beingmixed, a third valve means to control discharge of reconditioned sandfrom said mixing and mulling means, timed means arranged operable toautomatically operate said first valve means, said power-operated means,said second valve means, and said third valve means in timed relation toeach other and for predetermined periods of time for repetitiveoperation of said valve means and said power-operated means in operativecycles, means interposed between said first valve means and said mixingand mulling means to indicate the moisture content of sand flowing fromsaid source, and manual means operable at will and cooperable with saidtiming means to condition the supply of water during only apredetermined portion of each cycle of operation in accordance with theinformation on moisture content conveyed to the operator by saidmoisture content indicator.

4. Means operable in repetitive cycles for reconditioning sand, saidmeans comprising in combination a casing containing power-operatedmixing and mulling means, a first valve to control discharge ofconditioned sand from said casing, a hopper disposed above said casing,a second valve operable to control flow of sand from said hopper to saidcasing, means interposed between said second valve and said casing toindicate the moisture content of sand flowing from said hopper to saidcasing, water supply means including a third valve to supply water tosaid casing, timed means connecting said power-operated means, saidfirst valve, said second valve, and said third valve for automaticallyefiecting operation of said power means and said valve means in timedrelation to each other in operative cycles, and manual means operable atwill and cooperable with said timed means to condition the supply ofwater during only a predetermined portion of each cycle of operation inaccordance with the information on moisture content conveyed to theOperator by ALFRED C. CHRISTENSEN.

